TimkenNTA4860Needle Roller Thrust Bearing Cage and Roller Assembly, 3.000 x 3.750 x 0.0781 in, Steel Cage, 9-Piece Lot

Product Description

What this part is

A Timken NTA4860 needle roller thrust bearing — a flat cage-and-roller assembly in which needle rollers lie radially in a stamped steel cage and run between two flat thrust faces. It carries axial (thrust) load only, and it does it in a package 0.0781 in thick. That is the entire reason this bearing type exists: where a ball thrust bearing would need a quarter of an inch or more of axial space, a needle thrust assembly does the job in under a tenth.

Decoding the designation

NTA – Timken (Torrington) inch-series needle roller thrust cage-and-roller assembly. This is the rolling element pack, not a complete washered bearing.
48 – bore code, 48/16 = 3.000 in.
60 – outside diameter code, 60/16 = 3.750 in.
TRA / TRB – the companion hardened thrust washer numbers in the same size, TRA being the thinner and TRB the heavier race. They are separate part numbers.

Quantity and configuration

This listing is a bulk lot of 9 pieces — nine NTA4860 cage-and-roller assemblies. No thrust washers are included, and no snap ring. If the mating faces in your assembly are not themselves hardened and ground to at least 58 HRC, you need TRA4860 or TRB4860 washers on each side, ordered separately — running needle rollers directly against soft steel will brinell the face in short order. Many gearbox and transmission housings do provide a hardened face on one side, which is why the assembly is sold on its own.

Published ratings and mounting data

Bore: 3.000 in / 76.20 mm
Outside diameter: 3.750 in / 95.25 mm
Thickness: 0.0781 in / 1.98 mm (5/64 in)
Rows: 1, needle rollers, radial arrangement
Cage: stamped steel
Dynamic load rating: 56.5 kN / 12,700 lbf
Static load rating: 240 kN / 54,000 lbf
Limiting speed: 4,600 rpm
Operating temperature: -30 °C to 120 °C
Closure: open, no seals
Snap ring: not supplied

What these specs mean in practice

The very high static rating relative to the dynamic rating is characteristic of needle thrust bearings and is not a data error: the line contact of many rollers across a large mean diameter gives enormous static capacity, while the dynamic rating is limited by the sliding that occurs because rollers on a flat face cannot roll at a single correct speed across their whole length. That same geometry sets the speed limit — 4,600 rpm here — and it is why these are chosen for heavily loaded, moderate-speed thrust duties: gear pump end plates, transmission and planetary thrust faces, jack screws, swivel and turntable joints, crane hooks, automotive steering and clutch positions.

Fitting notes

Both running faces must be hardened, ground and flat, and they must be parallel — a needle thrust assembly transmits load across the full roller length, so any face taper concentrates load on one end of every roller. Keep the cage centred on the shaft or spigot; there is no inner or outer ring to locate it, so radial location is the surrounding hardware’s job. Lubricate before assembly and use a grease or oil suited to sliding as well as rolling contact.

Interchange guidance

Direct same-envelope equivalents: Koyo NTA-4860, Torrington NTA4860 (the same product before the Timken acquisition), NTN NTA4860, INA/Schaeffler AXK7595 in the nearest metric size, and the trade forms NTA 4860 and NTA-4860. INA AXK 75100 is often cross-listed for this part and is carried here as a searchable reference, but note the difference: AXK 75100 is 75 x 100 mm, which is 2.953 x 3.937 in — a metric size, not a dimensional match for 3.000 x 3.750 in. Match washers by number as well: TRA4860 and TRB4860 are the correct races for this assembly, and washers from an adjacent size will leave the roller ends unsupported.